28 May 1999

Best to worm earlier

PRODUCERS risk poorer liveweight gain potential when cattle are not wormed in early season.

Speaking at Grassland 99, Merial vet Andy Forbes said worms could reduce cattle appetite, meaning they ate less, and digested grass less well.

A Merial-funded study at IGER North Wyke, Devon, compared the performance of 20 autumn-born Holstein heifers, half of which were treated with a worm bolus before turnout, the other half left untreated.

While treated and untreated animals initially showed no difference in performance, by mid-July, daily liveweight gain for treated heifers was 0.8kg a day, whereas untreated heifers gained only 0.65kg a day. Treated heifers grazed for an hour-and-a-quarter longer each day, and, consequently, ate 3.5kg freshweight of grass more each day, said Mr Forbes.

"The untreated heifers were on paddocks with a very low worm count, but even so their appetite was affected by worm infection.

"In many cases, producers still prefer to worm cattle in July and move them on to clean pastures. While there is nothing wrong with that for worm control, it does mean that you could lose early season growth potential compared with worming before turnout."